Thursday, October 17, 2002

Dangerous times

He has developed a method called "geographic profiling, and it attempts to discern the "where" of serial killers in the way psychological profiling seeks the "who." Dr. Rossmo uses a computer to generate three-dimensional coloured maps, like topographical maps. But the peaks on his maps, shown in red, indicate something else: probability. Dr. Rossmo came up with the technique when he was a PhD candidate at Simon Fraser University 10 years go. His advisers, criminology professors Paul and Patricia Brantingham, had developed an algorithm to predict where a criminal would commit crimes based on where he or she lived, following what psychologists refer to as the least-effort principle. Inverting that model, Dr. Rossmo found he could zero in on 5 per cent or less of the "hunting area" covered by crime sites and superimpose a street map on it."

"In 1998, when sex-trade workers had been disappearing from Vancouver's Downtown Eastside, Dr. Rossmo, then a detective inspector with the department, suggested to his superiors that the community be warned of a serial killer and singled out a pig farm in Port Coquitlam and one of the farm's owners, Robert Pickton, as suspicious. His warnings were ignored and the resulting friction within the department earned the 20-year veteran a demotion, pulling the plug on the fledgling geographic profiling unit. In February, Vancouver police searched that same pig farm and have charged Mr. Pickton with the murder of 15 of the missing women."